The present invention relates to a new and improved apparatus for automatically displacing or adjusting the radial position of a cross-feed slide of a cross-feed head of a cutting machine containing a rotatable spindle for receiving or accommodating the cross-feed head. The cross-feed slide of the cross-feed head is arranged to be displaceable in a cross-feed direction by means of a displacement or adjustment drive and a displacement or adjustment mechanism. There also are provided a carriage accommodating the spindle and which is displaceable in a carriage displacement direction transversely with respect to the spindle and a numerical control.
An apparatus as described hereinbefore is already known in practice. The cross-feed slide of the cross-feed head is continuously displaceable during the rotation of the spindle. This occurs by means of a displacement drive mounted at a spindle carriage and provided for a displacement mechanism in the cross-feed head. The displacement mechanism comprises differential gearing to which may be inputted a displacement magnitute in the form of a timewise limited rotational speed difference. This rotational speed difference activates the displacement mechanism. The exact radial position of the cross-feed slide is determined by a measuring sensor at the workpiece and is inputted to the numerical control which derives therefrom the displacement magnitude.
When using such apparatus over longer periods of operation, heat is generated in the differential gearing which propagates through the cross-feed head and thus also affects the position of the tool. Errors result therefrom which are impermissible for finish-machining operations. Additionally, any errors in the displacement gearing will also affect the radial position of the tool. With such an apparatus there cannot be properly performed a roughing operation during which high cutting forces occur since the cross-feed slide cannot be clamped in its desired position. The actual radial position assumed by the tool after the displacement of the cross-feed slide is not checked in such apparatus.